[Rodney King]

In case you haven't noticed, they attack and have attacked anyone who doesn't believe their Islamic caliphate.

So why do they attack Saudi Arabia and Pakistan?

[NeoCaveman]

So why do they attack Saudi Arabia and Pakistan?

They aren't radical enough for the Islamists.

[liberte]

Because they are not Islamic governments. Saudi Arabia is a monarchy, and Pakistan is a military dictatorship. OBL and his ilk think the only acceptable dictators are people like themselves: devout, homicidal, intolerant, unmerciful followers of the “Religion of Peace”.

[SoCal Pubbie]

“So why do they attack Saudi Arabia and Pakistan?”

Because those countries don’t believe in the Caliphate either. They rather like their kingdom and nominal democracy, in both cases quite willing to do business with the infidels.

[rmlew]

Read the works of ibn Wahhab or Qutb.
They believe that the corrupt regimes have taken the Islamic states back to a "Jahillya" or pre-Islamic state, necessitating a Jihad against them.
(Note theis was the excuse the fundamentalists Saudi clan latched onto by sheltering Wahhab to go after the Hashemites and Ottomans.)